THE father of a man who killed himself after shooting another man in Ingleburn, Sydney, on Monday has been charged with discharging a firearm in an earlier incident the same day.

His son, Wayne Williams, shot three brothers, one of them fatally, at a signage business before shooting himself dead hours later at the scene.

Mr Williams' father, Peter, was bailed, unopposed, after a brief court appearance yesterday.

Police said Michael Bassal was shot dead and his brothers Terry and Mark were wounded by Wayne Williams with a semi-automatic firearm.

The shooting sparked a police lockdown of the area, where Peter Williams and Chantelle Strnad were both charged with not assisting police inquiries.

Police said they were investigating whether a business dispute had led to the shootings, as Ms Strnad owned the signage company and Wayne Williams and the three Bassal brothers worked there.

Possible links between Wayne Williams and outlaw motorcycle gangs were also being probed, police said.

Lawyers for the Bassal family said the shooting involving the three brothers was the result of a business transaction for signage and had nothing to do criminal activity.